In modern motor vehicles, which often comprise a plurality of convenience functions, there is a rising demand to be able to distinguish between the different users of the motor vehicle, in particular upon an actuation of control elements. For example, this applies, however is not limited to, a utilization of dual view or multi view displays, which depict different display contents in different viewing angles. For example, such dual view or multi view display Devices are arranged in motor vehicles in a center console between a driver and a co-driver. The driver and the co-driver may simultaneously observe differing display contents. When such a dual view or multi view display in addition is coupled with a touch-sensitive spatial resolution sensor and for example is formed as a touchscreen, such a user input may be detected by way of touching the display surface. Here, associated with the touching position is an action, function or the like which is correlated with a respective function, action or the like which is displayed at the touching position. It results therefrom that it is required for this purpose to detect which user, the driver or the co-driver, has touched the display surface.
Also in further operating scenarios in motor vehicles, which do not comprise a dual view or multi view display device, it is reasonable or required to carry out a user recognition. For example, in order to avoid a distraction of a driver from road traffic, while driving it is reasonable to limit the use of individual functionalities requiring a complex operation, for example those of a multimedia system, to a co-driver.
When user-specific settings are carried out control elements may be eliminated when a user recognition occurs. In the case of a seat heating control that is designed individually for each seat, for example one control element is sufficient, if in addition a user recognition is carried out which generates a user recognition signal indicating whether the driver or the co-driver has actuated the control element.
Different systems for a user recognition and a driver/co-driver discrimination, respectively, have been proposed in prior art.
For example, described in EP 1 710 672 A2 is a system comprising a user discrimination control and a method for operating a system comprising a personalized user control. The system has conductive surfaces which are arranged adjacent to each control element. A transmitter is connected to the conductive surfaces. The transmitter emits a unique signal to each conductive surface. Further, arranged nearby the users of the control elements are electrodes which are each coupled with a receiver. When the user actuates one of the control elements, a capacitive coupling of the respective unique signal into the body of the user is carried out. The user forms a HF transmission path between the conductive surface and the electrode. The signal received by the receiver is evaluated in order to output a user recognition signal which identifies the user as the driver or the co-driver.
Described in GB 2 428 094 A is a control device for an input device which distinguishes at least between a first and a second user based on a user recognition signal which is received from one of the users. For example, antennae are arranged in the seats for this purpose which are coupled with transmission units that generate differing high frequency signals. These are coupled into the user sitting on the seat by means of the respective antenna arranged in the seat and are transmitted via the body of the user. When one of the users touches the touchscreen the HF signal, transmitted by means of the body of the user forming a HF transmission path and coupled into the touchscreen, is measured. The coupled HF signal is evaluated and the user recognition is carried out by means of the evaluation of the HF transmission.
Such a system is reliable, however has the disadvantage, that high frequency signals are coupled into the users constantly, even when no actuation of a control element is intended or carried out.